Present-day communications systems, e.g. for voice, video, multimedia and/or data communications, frequently extend over a plurality of networks which may be based on different network technologies, e.g. different packet-switched or circuit-switched technologies. Here, it is not uncommon for individual networks of a large-scale communications system to be operated by network operators which are independent from one another, employing different, individual network operation strategies.
Different networks are frequently interconnected with the aid of network transit devices, referred to as “gateways”, in order to transmit data across the networks. A particular function of a gateway of this type is to adapt different data transmission methods of different connected networks to one another.
An important property of data transmission, in particular during a communications connection, is “quality of service”. The quality of service (QoS) of a data transmission may comprise different transmission and connection properties, e.g. transmission bandwidth, transmission speed and/or maximum or mean error rate or transmission delay.
Different methods are known, e.g. from ITU-T Recommendation H.323, for ensuring the quality of service of a communications connection. These methods, and the respective predefinable quality of service settings, are normally dependent on the network technology and the available transmission methods of a respective transport network. In a heterogeneous communications network extending over a plurality of different networks, network-specific methods for ensuring quality of service cannot readily adapt to one another across the networks, according to the currently known state of the art. Known methods for ensuring quality of service cannot normally be applied globally across heterogeneous communications networks of this type, or can only be applied if these methods and the associated quality of service settings are standardized across the entire communications network.
A potential object of the present invention is to indicate a method for cross-network support of quality of service features in heterogeneous communications networks.
The method is essentially implemented by a gateway device, i.e. a network transfer device, which is logically divided up into a gateway controller and one or, if necessary, more user data gateways. The use of a logically divided gateway device of this type, e.g. according to ITU-T Recommendation H.248, offers the advantage that the method can be very readily scaled to communications networks of different orders of magnitude, and is suitable in particular for heterogeneous, distributed network architectures. Whereas the gateway controller is used in particular for signaling evaluation, signaling processing and/or signaling conversion, user data in particular, e.g. voice data, video data, multimedia data and/or file data are transmitted and, if necessary, converted by the user data gateway.
Quality of service information, e.g. in the form of a quality of service message or a quality of service signal, is transferred by the gateway controller, depending on evaluated quality of service signaling to the user data gateway. Specific quality of service properties of connection segments coming into and/or going out from the user data gateway are evaluated by the user data gateway and, depending thereon, a quality of service setting is carried out according to the transferred quality of service information. For example, network-specific, interface-specific, connection-specific and/or quality of service type specific quality of service properties of the connection segments can be evaluated as quality of service properties.
The quality of service information can preferably be transferred by a protocol according to ITU-T Recommendation H.248, which is extended to include a quality of service information signaling element. Due to the extension, this signaling protocol which is particularly suitable for the communication of gateway components, can also be used to transfer quality of service information.
Alternatively, the quality of service information can be transferred according to the IETF standard by a “Media Gateway Control Protocol” (MGCP) which is extended to include a quality of service signaling information element.
According to an advantageous further development, the user data gateway can compare the quality of service properties of outgoing and incoming connection segments and, depending on the result of the comparison, can convert quality of service parameters allocated to these connection segments. In this way, for example, if the quality of service properties of an incoming connection segment of a connection differ from the quality of service properties of an outgoing connection segment of this connection, the quality of service parameters allocated to the incoming connection segment can be converted into the equivalent quality of service parameters for the outgoing connection segment. The conversion is preferably carried out in such a way that quality of service settings which are as similar as possible in terms of their effect are carried out for both connection segments. The conversion of the quality of service parameters depending on the comparison of the quality of service properties can be carried out by the user data gateway largely independently, i.e. without consultation with the gateway controller. No additional specific signaling is therefore required.
According to an advantageous embodiment, generic quality of service information can be transferred by the gateway controller to the user data gateway. Generic quality of service information refers in this context to information which is independent of the networks which transport user data, or which is at least not transport-network-specific. The transferred generic quality of service information is converted by the user data gateway depending on the connection-segment-specific quality of service properties into connection-segment-specific quality of service settings.
Instead of generic quality of service information, the gateway controller can also transfer specific quality of service information, which may, for example, be network-specific, interface-specific and/or quality of service type specific, to the user data gateway. The quality of service information conversion depending on the quality of service properties of the connection segments can be omitted in this case or replaced by a check to ascertain whether the specific quality of service information can be reconciled with the quality of service properties.
According to a further advantageous embodiment, the connection segments going out from the user data gateway can in each case be controlled by a specific data object which has quality of service parameters in the sense of an object-oriented program concept.
According to an additional advantageous further development, the gateway controller can retrieve connection-segment-specific quality of service properties from the user data gateway and can then transfer the quality of service information depending on the retrieved quality of service properties. The quality of service properties can preferably be retrieved before a connection is set up in order to negotiate the quality of service for the connection in advance depending on the available quality of service resources. Preliminary quality of service negotiation of this type is often referred to as the “look-ahead method”.
According to an additional advantageous further development, further quality of service information can be transferred, depending on a quality of service specification, from the gateway controller to one or more connection end points, e.g. a terminal device for voice, video and/or multimedia communications or to a multimedia-enabled personal computer. The quality of service specification may be defined here e.g. by the system administration or by the evaluated quality of service signaling. Quality of service settings of the connection end point can be defined with reference to the user data gateway through the transfer of the further quality of service information to a connection end point.